Features and Improvements
- Transient Stability: Completed the development of VHVDC_A1 model. It is no longer considered a Beta version and is ready for use.
- File Formats: Fixed several bugs reading and writing line short circuit data to a PWB file. If the line could not be found when loading, the parameters where not being loaded correctly and would produce access violations and a failure of the file read.
- Optimal Power Flow (OPF): During an AC OPF, fast-start commitment and decommitment was being checked upon completion of the very first optimization inner loop. This premature action could bias units to be committed or decommitted too early in the AC OPF iterations, especially when the initial optimization inner loop created more branch violations that had not been initially captured by the LP tableau. This has been changed to ensure that fast-start commitment or decommitment viability is checked only after all other controls and related constraints have reached an overall numerical optimum. In some situations this allows more fast-start units to be committed (or decommitted), ultimately leading to lower OPF system cost.
- Optimal Power Flow (OPF): For fast-start generation units currently with Status = Open, the correct sensitivity values were not being populated into the Linear Program Simplex tableau. This led to situations where a generator unit would not become committed even though it was actually favourable for it to be committed (i.e., it could actually relieve branch violations and reduce the overall OPF system cost). Fast start decommitment was not affected. For fast start commitment, it worked okay for situations where the area/superarea MW constraint or the cheaper cost of a fast start unit necessitated an action. However, prior to this patch, an intially Open fast start unit would not become committed if its cost was the greater than or equal to the cost of other generation units that were currently Closed in its respective area/superarea.
- Transient Stability: For VHVDC_A1, fixed initialization of the Vac1wInt state when operating is islanded mode (OpMode = 1)
- User Interface Dialogs: When scaling loads by Bus, Area, Zone, or Owner and using the Option to "Scale Only AGCable Load", if the present amount of Non-AGCable load is more than the New Value requested, then Simulator will change all the AGCable load to negative values to meet the request. A dialog box message now appears to warn the user that this is occurring.
- Weather: Bug fix to get the TimeStepLoadPWW to work with the HRR files (the error was in the 80m wind conversion).